The present invention relates to methods and devices for recording on an optical disk, such as a CD-R, CD-RW, CD-WO, MD or DVD, by use of light power, and more particularly to a technique for controlling the light power promptly with increased accuracy.
Among various types of known write-once and rewritable optical disks is one having a recording layer of dye or coloring material. Specifically, such dye-layer-type optical disks include a substrate that is coated with a film of dye-based recording material by use of the "spin coat" method. Thus, each of these dye-layer-type optical disks tends to have a nonuniform coating thickness across its radius, due to which its recording sensitivity would substantially differ between the inner and outer circumferential portions. Further, a fingerprint, dust or other foreign matter, adhering to the surface of the optical disk, would sometimes cause undue absorption or scattering of the recording laser light beam, thereby preventing satisfactory recording.
In Japanese Patent Laid-open Publication No. HEI-5-282672, there is proposed an improved optical disk recording method designed to avoid the above-mentioned inconvenience. Specifically, in the proposed optical disk recording method, a reflection of the recording laser light beam from the optical disk is constantly monitored, and the irradiation power of the light beam is controlled in accordance with the monitored reflection levels so that desired pits are formed in the optical disk in a constantly appropriate manner.
However, the proposed optical disk recording method is disadvantageous in that it can not promptly control the power of the laser light beam in an accurate manner, because sampling points of the reflection levels are not specifically set in the proposed method.